Apparatus and process for the refinement of biodiesel fuel

ABSTRACT

The present invention includes a method and apparatus for the production of biodiesel fuel from simple triglyceride sources, such as vegetable oil. In particular, the present invention incorporates a compact processor including a vapor recovery system for removing excess alcohols from the fuel, and thus promoting ASTM compliance. The vapor recovery system includes means for conserving and storing the excess alcohol for further use in the processing of biodiesel fuel. Additionally, a chemical cleaner in the form of an adsorbent material is introduced into the fuel prior to filtering in order to remove particulate matter and other impurities in the biodiesel fuel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of fuel productionand more specifically to the production of diesel fuel from triglyceridesources in a compact apparatus.

2. History of the Related Art

It is known in the art to use various oils as fuel for combustionengines. Rudolph Diesel recognized that vegetable oils could be used forthis purpose, particularly in his eponymous engines. In light of theescalating costs of petroleum-based fuels, there has been a great dealof attention paid to alternative fuels that will meet the needs of theheating and transportation industries. Willie Nelson, the famed countrysinger, has been a leading proponent of using pure vegetable oil as adiesel fuel, so much so that his tour bus runs entirely on this fuelsource.

Unfortunately, the use of pure vegetable oil does have some drawbacks.Most notably, the viscosity of vegetable oil is far too great to be ofuse in a combustion engine. To lessen the viscosity, the vegetable oilmust be heated prior to combustion. This requires preheating thevegetable oil, which can be done through the introduction of a specificfuel heater, or alternatively by configuring a parallel engine that runson petroleum-based fuel in order to generate the necessary heat to lowerthe vegetable oil viscosity.

Another type of biodiesel currently in use is based upon a processedvegetable oil that has a reduced viscosity at lower temperatures. Thetypical method of processing is known as transesterification, which is aknown process for creating esters from a triglyceride, such as vegetableoil. The byproducts of the transesterification process are generally thebiodiesel fuel, an excess amount of alcohol and some amount of glycerinthat is removed from the triglyceride base. Prior to use, the glycerinand excess alcohol must be removed in order to be compliant with ASTMfuel standards, shown below in Table 1. TABLE 1 Free Glycerin % 0.020maximum Total Glycerin % 0.240 maximum Flash Point, degrees C.   130degrees C., maximum Water and Sediment, Vol. % 0.050 maximum CarbonResidue, % 0.050 maximum Sulfated Ash, mass % 0.020 maximum KinematicViscosity, cSt at 40 degrees C.  1.9-6.0 Total Sulfur, mass %  0.05maximum Cetane Number   47 minimum Copper Corrosion No.    3 maximumAcid Number, mg KOH/gram  0.80 maximum Phosphorus, Mass % 0.001 maximum

Given the complexity of the testing and compliance initiatives that mustbe undertaken to meet the ASTM and other standards, the preliminaryfocus of research in the biodiesel fuel area has been directed atdistributed consumption. In short, the research focus has been relatedprimarily to vehicle propulsion, and the economies of scale required formass transportation have further limited the research into thisimportant area. To wit, the existing art is primarily directed towardslarge-scale processing and refining systems and methods in order tofacilitate a centralized processing and distribution system, likelymodeled after the petrochemical refinery system that this emergingtechnology wishes to displace.

A consequence of this industrial modeling is that the equipment andmethods utilized during the processing are prohibitively expensive forthe average consumer or entrepreneur. Traditional processing methodscall for the excess alcohol to be removed in one of two ways: throughflash evaporation or water washing. Each of these methods requiresexpensive hardware as well as additional fuel, heat and other resourcesfor operation. Water washing in particular leaves a producer with a verylarge volume of wastewater that is irretrievably tainted with excessalcohol. Moreover, once the alcohol is removed in either of thesemanners, it is generally not reusable in the processing of morebiodiesel fuel. As such, the current methods for removing excess alcoholfrom biodiesel fuel are simply impracticable for the small business andindividual consumer.

While such capital-intensive processes may make sense for largeoperations that are attempting to produce vast quantities of fuel, theaforementioned technology essentially prohibits the distribution ofsmall-scale, local refineries that can be used to generate smalleramounts of fuel for such tasks as home heating, electricity generationand emergency generators. Moreover, the current state of the artrequires systems and hardware that belie the intentions of alternativefuel, i.e. mass production and refinement may in time lead to higherprices as the distribution channels become more complicated.

As such, the state of the art is ill suited for combining thedistribution and processing systems and methods into a single saleableproduct that would allow the consumer control over the production anddistribution of biodiesel fuel on a smaller, individualized scale. Giventhe foregoing, what is needed in the art is an improved method andapparatus for the processing of a biodiesel fuel that eliminates theinefficiencies and expense associated with current technology. Moreover,there is a need in the art for a method and apparatus for the processingof biodiesel fuel that maximizes the usable output through the efficientand conscientious use of the raw materials. Lastly, there is a need inthe art for a method and apparatus for the processing of biodiesel fuelthat can successfully integrate the production and distribution of theend product such that individual consumers, businesses and entrepreneurscan make use of this energy source.

SUMMARY OF THE INVENTION

Accordingly, the present invention includes a method and apparatus forthe production of biodiesel fuel on a distributable scale. Inparticular, the apparatus of the present invention includes a system ofvessels that are connected through pumping mechanisms, valve mechanismsand filtration means for heating, mixing and moving the biodiesel fuelduring processing. A second of the vessels is sealed and insulated inorder to preserve any excess alcohol in a vapor state such that it canbe removed through a vapor recovery system. Unlike the prior art, thevapor recovery system of the present invention allows a user toefficiently recover excess alcohol and store it for later use in theprocessing of biodiesel fuel. As such, the apparatus of the presentinvention is particularly well suited for use by individual consumersand businesses for supplying fuel for their heating and energy needs.

The present invention also includes a chemical cleaning step thatintroduces an adsorbent material into the refinement process. Unlike theprior art however, the adsorbent material in the present invention isintroduced following the vapor-recovery of the excess alcohol, whichimproves the performance of the adsorbent material, and thus results ina cleaner, more efficient biodiesel product.

As described in detail below, the present invention incorporateschemical compounds that are known in the prior art into a unique methodan apparatus that are specifically adapted for rendering an ASTMcompliant product. The combination of the vapor recovery mechanism withthe chemical cleaning of the fuel significantly aids in this regard andthus permits biodiesel fuel consumers to become biodiesel fuel producersas well. In sum, the present invention, both in processor andmethodology, will allow individual consumers to have access to the meansof production of their own energy.

Combined with the increased efficiency resulting from the reuse of thealcohol component of the fuel, the present invention will result in theproduction of biodiesel at the point of use, as opposed to the currentsystem of centralized refinement and distribution. It is thereforeanticipated that users of the present invention will benefit fromreduced fueling costs as individual consumers enter the energyproduction market. These and various other benefits of the presentinvention are detailed below in discussing the preferred embodimentswith reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a compact apparatus for therefinement of biodiesel fuel in accordance with the present invention.

FIG. 2 is a flowchart depicting a process for the refinement ofbiodiesel fuel in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention solves the problems noted above by combining acompact processor design with a novel and efficient method for refiningbiodiesel fuel. In its preferred embodiments, the present invention isadapted for use in any number of locations; and unlike the systems andmethods known in the art, the present invention is particularlywell-suited for applications in which the processing and distribution ofthe biodiesel fuel are integrated.

FIG. 1 is a schematic illustration of a biodiesel fuel processor 10 inaccordance with a preferred embodiment of the present invention. Theprocessor 10 includes a first vessel 12 and a second vessel 14 that arecoupled through a series of pipes and valves described in detail below.A circulating pump 16 is disposed between the first vessel 12 and thesecond vessel 14 for creating the flow of materials between therespective vessels. A first valve 18, a second valve 20, and a thirdvalve 22 are disposed at selected intervals for controlling the flow ofmaterials between the first vessel 12 and the second vessel 14. Inpreferred embodiments, the processor further includes a filter 46 thatis serially disposed between the first vessel 12 and the second vessel14 for filtering the materials at various stages during the processing,including the final stage when the filter 46 directs the biodiesel to afuel container 48 configured for receiving, storing and dispersing thefuel during use.

The pump 16 is coupled to a first port 23 that transmits materials fromthe first vessel 12 into circulation. A second port 24 transmitsmaterials from the second vessel 14 into the pump 16. The pump 16includes an exit port 25 that is further coupled to the first valve 18,which is adapted to control where the circulating materials are directedthereafter.

A hot water heater 26 or other suitable heating means is coupled to asecond pump 28 that transmits a heated fluid into the first vessel 12for heating the materials therein. In preferred embodiments, a heatingcoil 30 is disposed within the first vessel 12 for radiantly heating themixture to a specified temperature as discussed in detail below. Theheater 26 preferably runs on a closed loop for maximum efficiency andtemperature regulation.

The second vessel 14 is connected to a vacuum gauge 40 that is in fluidcommunication with a vacuum pump 42 and a vacuum tank 44. The secondvessel 14 is preferably insulated and vacuum-sealed so as to maintain aconstant temperature and pressure therein.

The initial mixture forming the biodiesel is comprised of threecomponents that are known in the art. A triglyceride 32, an alkalinecatalyst 34 and an alcohol 36 are all placed in the first vessel 12 andheated to a proscribed temperature as discussed further here. Thealcohol 36 is preferably received at least in part from recycled alcoholpresent in the vacuum tank 44 noted above. In preferred embodiments, theexcess alcohol 36 from the processing reactions is removed, stored, andmade available for later use according to the methodology describedfurther herein.

Suitable triglycerides 32 are derived from both plant and animalsources, including canola oil, soybean oil, rapeseed oil, palm oil,coconut oil, corn oil, cottonseed oil, mustard oil, used cooking oils,float grease from wastewater treatment plants, beef tallow and porklard, soapstock, crude oils, and so-called “yellow grease”, which isanimal or vegetable fats derived from the preparation of food. Inpreferred embodiments, the triglyceride is a vegetable oil, such ascanola or soybean oil, or yellow grease oil that can be readily procuredfrom local restaurant establishments. Given the level of particulatesthat are generally present in yellow grease, it is more preferred thatthe triglyceride 32 be selected from a known vegetable oil. The alkalinecatalyst 34 is preferably potassium hydroxide, although sodium hydroxideis a suitable alternative. The alcohol 36 is preferably methanol, butethanol or propanol may also be used in the present invention.

The processor 10 of the present invention further comprises a source ofan adsorbent material 38, preferably housed in a third vessel (notshown) connected to the first vessel 12 for ease of use. A preferredadsorbent material 38 is magnesium silicate, which is commerciallyavailable under the brand name Magnesol®, a product of the Dallas Groupof America, Inc., Whitehouse, N.J. The chemical properties of Magnesol®are described in detail in U.S. Pat. Nos. 4,681,768 and 5,006,356. Theadsorbent material 38 is a chemical cleaner that is preferablyintroduced into the biodiesel fuel after removal of any excess alcoholcontent. The adsorbent material 38 removes various impurities that wouldotherwise render the fuel noncompliant with ASTM and similar foreignfuel standards. Such impurities include soap, colors, odors, excesscatalyst, metals, free triglycerides, sulfur, phosphorous and othermetals, acids or sediments.

In operation, the processor 10 operates multiple circuits for theheating, cleaning and recycling of the biodiesel fuel and its variousbyproducts. In a preferred embodiment, the first tank 12 receivespredetermined portions of the triglyceride, 32, the alkaline catalyst 34and the alcohol 36. This initial mixture is heated by the hot waterheater 26 to a specified temperature for a specified time period duringwhich the initial reaction is completed. The typical byproducts of thisreaction include the biodiesel fuel, a glycerin, some excess alcohol 36,and some amount of impurities described above. The glycerin may betapped from the first vessel 12 and removed via an exit port 31.

The processor 10 of the present invention is further configured forpre-filtering the triglyceride 32, particularly if it is of the yellowgrease variety. In doing so, the triglyceride 32 is released into thefirst vessel 12 without any other reactants. The pump 16 removes thetriglyceride 32 and routes it through the filter 46 by closing the firstvalve 18, opening the second valve 20 and closing the third valve 22. Inthis manner, the triglyceride 32 is filtered to remove any particulateslarger than 20 microns in diameter. More preferably, the filter 46 isconfigured for filtering at 5 microns. Upon completion of any initialfiltering step, the triglyceride 32 is returned to the first vessel 12where it is mixed with the other reactants as described above.

Upon completion of the initial reaction, the pump 16 is activated formoving the biodiesel fuel and remaining byproducts to the second vessel14. As shown in FIG. 1, this can be accomplished by closing the firstvalve 18 and closing the second valve 20, which will cause the productto enter the second vessel 14. As noted above, the second vessel 14 ispreferably vacuum-sealed and insulated, so as to maintain a specifiedpressure and temperature profile. In particular, the second vessel 14must be sufficiently well sealed and heated so as to maintain the excessalcohol 36 in a gaseous state. Upon satisfaction of this state, thevacuum pump 42 is engaged for removing the excess alcohol 36 in itsvapor form and channeling it to the vacuum tank 44, at which point itcan be cooled and condensed into a liquid state for reuse by theprocessor 10. Preferably, the conduit (not shown) linking the vacuumpump 42 and the vacuum tank 44 is cooled in order to speed thecondensation and recovery process. Conventional cooling means, such as awater jacket (not shown) disposed about the conduit can be used for thispurpose.

After vapor removal of the excess alcohol 36, the biodiesel fuel and itsremaining byproducts are routed from the second vessel 14 back into thefirst vessel 12 via the pump 16 by opening the first valve 18. When theresultant mixture is in the first vessel 12, the adsorbent material 38is added for a final cleaning and removal of impurities. During thecleaning reaction, the first vessel 12 is maintained at a specifiedtemperature for a predetermined amount of time, as described furtherbelow. Following the chemical cleaning, the biodiesel fuel is removedfrom the first vessel 12 and directed to the filter 46 through the pump16 by closing the first valve and opening the second valve 20 and thethird valve 22. The filter 46 is preferably adapted for filteringparticulates less than 20 microns, and more preferably the filter 46 isadapted for filtering at 5 microns, thus cleansing the biodiesel fuel ofany remaining particulates. After filtering, the biodiesel fuel isdirected into the fuel container 48 for storage and later use.

The processing methodology of the present invention is discussed withreference to FIG. 2, which is a flow chart depicting a process for therefinement of biodiesel fuel in accordance with the present invention.The method of the present invention is best practiced with the apparatusof the present invention, described with respect to its preferredembodiments above. Moreover, given the unique characteristics, themethod of the present invention is preferably, although not necessarily,practiced sequentially according to the flowchart of FIG. 2.

Beginning with step S102, the method of the present invention includesdepositing the triglyceride in the first vessel 12. As noted above, thetriglyceride is preferably a vegetable oil, such as corn or soybean oil.The size of the first vessel 12 is preferably between 50 and 75 gallons,thereby promoting the wide distribution of the processor 10 itself asopposed to merely distributing the biodiesel refined in the processor,as is currently the norm.

In step S104, the triglyceride is heated to between 115 and 125 degreesFahrenheit in order to reduce its viscosity. As discussed above, themeans for heating can include any conventional means, but mostpreferably includes a closed-loop water heater that is highly efficient,compact and easy to regulate. Preferably, the triglyceride is heated toapproximately 120 degrees Fahrenheit for optimum mixing of the biodieselreactants.

In step S106, a solution of the alcohol and alkaline catalyst iscreated. Preferably, the alcohol is methanol and the alkaline catalystis potassium hydroxide, although the alternative reactants discussedabove are also suitable. In a preferred embodiment, between nine and tengallons of alcohol receive between 1.25 and 1.5 kilograms of potassiumhydroxide, which is let to stand until the latter is fully dissolvedwithin the former. Upon dissolution, the alcohol-alkaline catalystsolution is introduced into the first vessel 12 wherein it reacts withthe triglyceride, as shown in Step S108. The mixture is circulatedthrough the first vessel 12 for a time period ranging between sixty andninety minutes, preferably about 75 minutes.

In Step S110, the contents of the first vessel 12 are permitted tosettle and separate by phase. This settling phase will take anywherebetween eight and twelve hours, at which time a film of glycerin willhave formed at the bottom of the first vessel 12. In step S112, theglycerin is removed from the first vessel 12 in a manner described aboveusing the exit port 31. In step S114, the pump 16 is activated and thenecessary valve mechanisms are initiated to transfer the remainingcontents of the first vessel 12 to the second vessel 14.

The second vessel 14 is preferably insulated and vacuum-sealed in orderto maintain the excess alcohol in a gaseous phase. Once within thesecond vessel 14, step S116 requires the removal of the excess alcohol.A vacuum pressure is applied to the contents therein in order to extractthe excess alcohol in its gaseous phase, preferably using the apparatusdiscussed in detail above. The vacuum pump 42 preferably operatesbetween 0.3 and 0.6 cubic feet per minute, and most preferably thevacuum pump 42 recovers the excess alcohol at approximately 0.45 cubicfeet per minute.

In particular, in step S116 it is essential that the second vessel 14 beinsulated in order to maintain the mixture at a temperature greater than100 degrees Fahrenheit so as to insure that the excess alcohol remains avapor. By vacuum sealing the second vessel 14, the present inventionassures a complete and efficient removal of the excess alcohol in such amanner that it is ready for reuse, and thus deviates from the prior artthat utilizes flash evaporation and water washing in order to bring thefuel into ASTM compliance. After the excess alcohol is recovered, it ispreferably condensed and stored for further use in step S106 of thepresent invention. That is, once the excess alcohol has been recoveredin its vapor form, it can be cooled and reused by the present inventionin the refinement of more biodiesel product.

Following the vapor removal of the excess alcohol, step S118 recitesthat the mixture is transferred back to the first vessel 12 by the pump16 and the necessary valve mechanisms described above. In step S120,between 3 and 3.5 kilograms of an adsorbent material is introduced tothe mixture in order to chemically cleanse the biodiesel prior to use.The chemical cleanse preferably continues for approximately 30 minutes.As noted above, the adsorbent material is preferably magnesium silicate,which is commercially available under the brand Magnesol®. Following thechemical cleaning, the biodiesel product is filtered through the filter46 as described above in step S122. The filter 46 will preferably beconfigured for filtering particulate matter greater than 20 microns indiameter, and more preferably the filter will remove all waste productthat is greater than 5 micron is diameter. After the filtration step,the biodiesel fuel is ready for storage and use by the user of thepresent invention.

As described herein, the present invention includes a method ofprocessing a biodiesel fuel and a processor that is configuredspecifically for the method. In particular, the processor and method ofthe present invention incorporates the novel use of a vapor recoverysystem in order to more efficiently and effectively recover any excessalcohol from the initial reaction. Moreover, the present inventionreadily allows for the excess alcohol to be reused in the processing ofadditional biodiesel. Moreover, the size and efficiency of the presentinvention allows for individual users to produce biodiesel in remotelocations, as opposed to relying on large-scale refineries anddistribution channels for their fuel needs.

In particular, the combination of the vapor recovery system and thechemical cleaning mechanisms allow individual users to process biodieselthat is ASTM compliant, and thus the present invention obviates the needfor the current methods of production and distribution. While thepresent invention is best carried out in a compact format, it isnoteworthy that the principles described herein are equally applicableto any size biodiesel processor. In particular, the processor and methodof the present invention could alternatively be scaled up ten-fold, suchthat each of the first and second vessels have a capacity ofapproximately 500 gallons. It is a feature of the present invention thatsuch an increase in capacity would not dramatically increase the costsof establishment, operation, or maintenance. That is, aside from largervessels, the marginal costs of increasing the volume and efficiency ofthe respective pumps and filters is significantly less than it wouldotherwise be for a traditional biodiesel-processing unit.

Accordingly, although the present invention has been described hereinwith reference to specific preferred embodiments, including a best modeof practice, it should be understood that design changes, scalemodifications and insignificant alterations could be devised by thoseskilled in the art without departing from the scope and spirit of thepresent invention as defined by the following claims.

1. A method for refining a biodiesel fuel comprising: providing atriglyceride base; reacting the triglyceride base with a solutionincluding an alcohol and an alkaline catalyst, thereby producing abiodiesel fuel portion and an excess alcohol portion; recovering theexcess alcohol portion; cleansing the biodiesel fuel portion throughcontact with an adsorbent material; and filtering the biodiesel fuelprior to use.
 2. The method of claim 1 wherein the triglyceride base isvegetable oil, the alcohol is methanol, and the alkaline catalyst ispotassium hydroxide.
 3. The method of claim 1 wherein the adsorbentmaterial is magnesium silicate.
 4. The method of claim 1 wherein thestep of recovering the excess alcohol portion comprises retrieving theexcess alcohol through vapor recovery.
 5. The method of claim 4 whereinthe step of retrieving the excess alcohol through vapor recoveryincludes providing a vacuum pump for recovering the excess alcohol in agaseous state.
 6. The method of claim 1 wherein the step of reacting thetriglyceride base with the solution including the alcohol and thealkaline catalyst includes the step of heating the triglyceride base,the alcohol and the alkaline catalyst to a temperature between 115 and125 degrees Fahrenheit.
 7. The method of claim 1 wherein the step ofrecovering the excess alcohol portion includes the step of heating theexcess alcohol portion to a temperature between 95 and 105 degreesFahrenheit.
 8. The method of claim 1 wherein the step of filtering thebiodiesel fuel prior to use includes passing the biodiesel fuel througha filter having a pore size between 5 and 10 microns.
 9. The method ofclaim 1 further comprising the step of filtering the triglyceride baseprior to reacting the triglyceride base with the solution including thealcohol and the alkaline catalyst, wherein filtering the triglyceridebase includes passing the triglyceride base through a filter having apore size between 5 and 10 microns.
 10. A biodiesel fuel processorcomprising: a first vessel containing heating means for heating a fuelcomprising a mixture of a triglyceride, an alcohol and an alkalinecatalyst; a second vessel coupled to the first vessel, the second vesselreceiving the fuel after an initial heating phase, the second vesselcontaining a heated fuel portion and an excess alcohol portion; a vacuumpump coupled to the second vessel, the vacuum pump adapted forrecovering the excess alcohol portion from the second vessel; and afilter coupled to the second vessel, the filter adapted for receivingand filtering the heated fuel portion from the second vessel.
 11. Thebiodiesel fuel processor of claim 10 further comprising a third vesselcoupled to the first vessel, the third vessel containing an adsorbentmaterial for introduction into the first vessel for cleansing the heatedfuel portion.
 12. The biodiesel fuel processor of claim 11 wherein theadsorbent material is magnesium silicate.
 13. The biodiesel fuelprocessor of claim 10 wherein the triglyceride is vegetable oil.
 14. Thebiodiesel fuel processor of claim 10 wherein the alcohol is methanol.15. The biodiesel fuel processor of claim 10 wherein the alkalinecatalyst is potassium hydroxide.
 16. The biodiesel fuel processor ofclaim 10 wherein vacuum pump is adapted for retrieving the excessalcohol portion in a gaseous state.
 17. The biodiesel fuel processor ofclaim 10 further comprising a vacuum tank for containing the excessalcohol portion, the vacuum tank coupled to the vacuum pump andreceiving the excess alcohol portion there from.
 18. The biodiesel fuelprocessor of claim 10 wherein the first vessel has a capacity between 50and 75 gallons.
 19. The biodiesel fuel processor of claim 10 wherein thesecond vessel has a capacity between 50 and 75 gallons.
 20. Thebiodiesel fuel processor of claim 10 wherein the vacuum pump has arecovery rate between 0.3 and 0.6 cubic feet per minute.